Danger Dude said:
Actually both Hp numbers are way off for V6 stangs. Flowmaster being a Chambered muffler will give a stock V6 almost zero HP. Magnaflows, Dynomax ultraflows or Borla's are flow thru design and will give you a little hp in the 2 to 5 HP range at best. Dont get confused by HP claims with V8 motors some like Cobra's can see a 15 or more HP gain.
As far as trusted Dynomax has been around the longest, both Magnaflow and Flowmaster started in the early 80's
He's right! Most any 2.25" true dual exhaust system on a V6 will make the
same HP, since they are designed for more like 302 cubic inch instead of 232.
Most louder systems will develop less backpressure as well, which generally
reduces low-end torque. I personally like Warlocks for a dual-personality setup
because they are relatively quiet until you remove the caps and then they
are really loud! And they make great power at the track with a 5 speed
(since you can launch higher and will not miss the low end)
A bigger or less restrictive system will not make more HP on a V6, but it may
very well reduce low end torque as most dual exhaust systems are geared
towards V8's that are 281 cubes and bigger.
So choose your sound and get it in a 2.25" size, and you will be set!